import parseKeys from "../parse-asn1";
import mgf from "./mgf";
import xor from "./xor";
import BN from "../bn.js";
import crt from "../browserify-rsa";
import createHash from "../create-hash";
import withPublic from "./withPublic";
function oaep(key, msg) {
    var k = key.modulus.byteLength();
    var iHash = createHash('sha1').update(Buffer.alloc(0)).digest();
    var hLen = iHash.length;
    if (msg[0] !== 0) {
        throw new Error('decryption error');
    }
    var maskedSeed = msg.slice(1, hLen + 1);
    var maskedDb = msg.slice(hLen + 1);
    var seed = xor(maskedSeed, mgf(maskedDb, hLen));
    var db = xor(maskedDb, mgf(seed, k - hLen - 1));
    if (compare(iHash, db.slice(0, hLen))) {
        throw new Error('decryption error');
    }
    var i = hLen;
    while (db[i] === 0) {
        i++;
    }
    if (db[i++] !== 1) {
        throw new Error('decryption error');
    }
    return db.slice(i);
}
function pkcs1(key, msg, reverse) {
    var p1 = msg.slice(0, 2);
    var i = 2;
    var status = 0;
    while (msg[i++] !== 0) {
        if (i >= msg.length) {
            status++;
            break;
        }
    }
    var ps = msg.slice(2, i - 1);
    if ((p1.toString('hex') !== '0002' && !reverse) || (p1.toString('hex') !== '0001' && reverse)) {
        status++;
    }
    if (ps.length < 8) {
        status++;
    }
    if (status) {
        throw new Error('decryption error');
    }
    return msg.slice(i);
}
function compare(a, b) {
    a = Buffer.from(a);
    b = Buffer.from(b);
    var dif = 0;
    var len = a.length;
    if (a.length !== b.length) {
        dif++;
        len = Math.min(a.length, b.length);
    }
    var i = -1;
    while (++i < len) {
        dif += (a[i] ^ b[i]);
    }
    return dif;
}
export default (function privateDecrypt(privateKey, enc, reverse) {
    var padding;
    if (privateKey.padding) {
        padding = privateKey.padding;
    }
    else if (reverse) {
        padding = 1;
    }
    else {
        padding = 4;
    }
    var key = parseKeys(privateKey);
    var k = key.modulus.byteLength();
    if (enc.length > k || new BN(enc).cmp(key.modulus) >= 0) {
        throw new Error('decryption error');
    }
    var msg;
    if (reverse) {
        msg = withPublic(new BN(enc), key);
    }
    else {
        msg = crt(enc, key);
    }
    var zBuffer = Buffer.alloc(k - msg.length);
    msg = Buffer.concat([zBuffer, msg], k);
    if (padding === 4) {
        return oaep(key, msg);
    }
    else if (padding === 1) {
        return pkcs1(key, msg, reverse);
    }
    else if (padding === 3) {
        return msg;
    }
    else {
        throw new Error('unknown padding');
    }
});
